Non-specific immunosuppressive therapy of man is associated with considerable morbidity. Some regimens are superior to others. The New Zealand mice offer a convenient model for studying drug comparisons prior to study in patients. It would be even more desirable to treat patients in an immunologically more specific manner. Toward that end we have been treating New Zealand mice with activators of suppressor cells and with suppressor cells themselves. Preliminary results with NZB mice suggest that the autoimmune process can be markedly retarded by such specific immunosuppression. These studies will be pursued and an attempt will be made to obtain a soluble suppressor substance so that the technique might be applicable to man.